On the Nature of Black Holes in Loop Quantum Gravity

A genuine notion of black holes can only be obtained in the fundamental framework of quantum gravity resolving the curvature singularities and giving an account of the statistical mechanical, microscopic degrees of freedom able to explain the black hole thermodynamical properties. As for all quantum systems, a quantum realization of black holes requires an operator algebra of the fundamental observables of the theory which is introduced in this study based on aspects of loop quantum gravity. From the eigenvalue spectra of the quantum operators for the black hole area, charge and angular momentum, it is demonstrated that a strict bound on the extensive parameters, different from the relation arising in classical general relativity, holds, implying that the extremal black hole state can neither be measured nor can its existence be proven. This is, as turns out, a result of the specific form of the chosen angular momentum operator and the corresponding eigenvalue spectrum, or rather the quantum measurement process of angular momentum. Quantum mechanical considerations and the lowest, non-zero eigenvalue of the loop quantum gravity black hole mass spectrum indicate, on the one hand, a physical Planck scale cutoff of the Hawking temperature law and, on the other hand, give upper and lower bounds on the numerical value of the Immirzi parameter. This analysis provides an approximative description of the behavior and the nature of quantum black holes

Zero Order Correction of Shift-multiplexed Computer Generated Fourier Holograms Recorded in Incoherent Projection Scheme

Application of computer holography methods provides the possibility to obtain the high quality holograms of objects that exist as digital models without the necessity of complex and high precision optical schemes. Computer generated Fourier holograms (CGFH) are widely used for record and optical restoration of relatively simple 2D raster objects. Application of incoherent photolithography methods such as incoherent projection allows the record of CGFHs as micro-holograms onto the photosensitiv medium with desired reduction of hologram sizes using relatively simple optical setup. The reconstruction optical schemes of CGFHs can be implemented in augmented reality displays and optical sight indicators. In this article the specificity of CGFH shift-multiplexed record process and particularly the method of zero order correction is discussed. Keywords: computer generated hologram, Fourier hologram, incoherent projection scheme

Anticorrelation between temperature and fluctuations in moderately damped Josephson junctions

We study the influence of dissipation on the switching current statistics of moderately damped Josephson junctions. Different types of both low- and high- $T_c$ junctions with controlled damping are studied. The damping parameter of the junctions is tuned in a wide range by changing temperature, magnetic field, gate voltage, introducing a ferromagnetic layer or in-situ capacitive shunting. A paradoxical collapse of switching current fluctuations occurs with increasing $T$ in all studied junctions. The phenomenon critically depends on dissipation in the junction and is explained by interplay of two counteracting consequences of thermal fluctuations, which on the one hand assist in premature switching into the resistive state and on the other hand help in retrapping back to the superconducting state. This is one of the rare examples of anticorrelation between temperature and fluctuation amplitude of a physically measurable quantity.Comment: 17 pages, 20 figure

Collapse of thermal activation in moderately damped Josephson junctions

We study switching current statistics in different moderately damped Josephson junctions: a paradoxical collapse of the thermal activation with increasing temperature is reported and explained by interplay of two conflicting consequences of thermal fluctuations, which can both assist in premature escape and help in retrapping back into the stationary state. We analyze the influence of dissipation on the thermal escape by tuning the damping parameter with a gate voltage, magnetic field, temperature and an in-situ capacitor.Comment: 4 pages, 4 figure

Discrimination between the superconducting gap and the pseudo-gap in Bi2212 from intrinsic tunneling spectroscopy in magnetic field

Intrinsic tunneling spectroscopy in high magnetic field ($H$) is used for a direct test of superconducting features in a quasiparticle density of states of high-$T_c$ superconductors. We were able to distinguish with a great clarity two co-existing gaps: (i) the superconducting gap, which closes as $H \to H_{c2}(T)$ and $T\to T_c(H)$, and (ii) the $c$-axis pseudo-gap, which does not change neither with $H$, nor $T$. Strikingly different magnetic field dependencies, together with previously observed different temperature dependencies of the two gaps ~\cite{Krasnov}, speak against the superconducting origin of the pseudo-gap.Comment: 4 pages, 4 eps figure